Adjustable reactance components



April 11, 1967 l N. BERMAN ADJUSTABLE REACTANCE COMPONENTS Filed Feb. l, 1966 fla I NVENTOR.

United States Patent() 3,313,990 ADJUSTABLE REACTANCE COMPONENTS Nelson Berman, Far Rockaway, N.Y., assignor, by mesne assignments, to Stratford Retreat House, White Plains, N.Y., a religious organization of New York Filed Feb. 1, 1966, Ser. No. 532,826 1 Claim. (Cl. 317-249) My invention relates to improvements in adjustable electronic components.-

In particular my invention relates to improvements in adjustable electronic components of the tubular coaxial type.

In accordance with my invention, I provide an elongated, hollow casing having mounted thereon one or more l fixed elements of the electronic component. I provide a movable element which is slidably positioned wit-hin the casing and can be moved by means of an axially extending adjustment device which include a screw.

In the manufact-ure of miniature precision adjustable electronic components it is necessary to hold very close tolerances between fixed and moving parts. For example, trimmer capacitors `are commonly made with radial clearance of less than .0002 betwen certain parts. With know-n types of adjustable components these close tolerances impose alignment requirements during assembly which are diliicult to achieve using 4mass production techniques. Hence these close tolerances have resulted in breakage and jamming which increase cost-s and have resulted in decreased reliability or the components While in use.

In my invention the moveable elements is flexibly supported so that the stresses vdue to relative movement of close fitting, non-concentric and unaligned rigidly held parts are avoided.

'It is accordingly an object of my invention to provide more economical and more reliable adjustable electronic components.

A further object of my invention is to provide a novel adjustment mechanism which minimizes backlash and provides a uniform, constant adjustment torque.

A still further object of my invention is to provide adjustable electronic components which have sealed interiors so that the components will not be adversely affected by environmental changes and by contamination.

Other objects and advantages of my invention will become apparent from the following description in conjunction with the annexed drawings, in which preferred embodiments are disclosed.

In the drawings,

FIGURE 1 is a longitudinal section of one embodiment of the invention, a trimmer capacitor.

FIGURE 2 is a longitudinal section of a modified construction of the adjusting mechanism of the invention.

FIGURE 3 is a longitudinal section of a second embodiment, a trimmer capacitor.

FIGURE 4 is a longitudinal section of another modied construction ofthe adjusting mechanism of the invention.

Referring to FIGURE l, the exemplary component 1 is a trimmer capacitor of the panel mounted type. It has a hollow mounting bushing 8 with external threads 23 engaging with mounting nut 12. The flange 9 extending from the bushing 8 in conjunction with nut 12 permits mounting the component in a panelin the vconventional manner.

A hollow elongated cylinder 6 made of material having a high dielectric constant, such as glass or ceramic, is mounted on flange 9 by optional means of solder 11. The cylinder 6 has a metalized band 5 which is the fixed electrode of the capacitor 1. The band 5 coacts with the ICC dielectric cylinder l6 andthe internal piston 13 to establish the capacitive action. A second metalized band 7 is provided to permit the attachment of the cylinder 6 to the flange 9. A metallic cap 2 attached by solder 4 to band 5 serves to seal one end of the cylinder 6 and to provide a terminal post 3 for electrode band 5.

The tuning piston 13 is attached to one end of a exible cylindrical rod or wire 14 having .a circular cross section. The other end of the rod or wire is attached to dis-c 16 which has an external screw thread 24. The ends of spring 18 are immovably attached to disc 16 and to.

adjustment disc 17. Adjustment disc 17 has the external screw thread 25 and slot 27 for accommodating a screwdriver or other adjustment device. During assembly of the component, the spring 18 is slightly compressed while the two dis-cs 16 and 17 are threaded into the bore 19. Thereafter, the spring exerts force on the discs 16 and 17 which tends to move them in opposite directions until the external threads 24 and 25 'are firmly abutted against the internal screw thread 20. It may be seen that the axial tension between the discs 16 and 17 on the internal screw 20 minimizes the backlash encountered when adjustment disc 17 is rotated. Hence, any rotation of the disc 17 results in a corresponding axial movement of the piston 13 without any lost motion. The amount of the axial movement of piston 13 for a given rotation of disc 17 is determined by the pitch of the sscrews 20, 24 and 25.

The discs 16 and 17 and the spring 18 coact with the internal thread 20 to provide frictional resistance to turning the adjust disc 17 and the connected elements spring 1S, disc 16, rod 14 and piston 13. This friction-al resistance or tur-ning torque provides mechanical and electrical stability under conditions of shock and vibration.

The tuning piston 13 is hollow. It is` proportioned so that its outside diameter is a close fit in the dielectric cylinder `6 and its inside diameter is greater than the outside diameter of the bushing 10 permitting the piston 13 to telescope over the bushing 10.

The end of bore 19 in bushing 10 has an unthreaded portion 21 which is of smaller `diameter than the threaded portion. The unthreaded portion of the bushing 21 is counterbored to accommodate an O-ring 26 made of rubber or other flexible resilient material. The O-ring 26 is proportioned so that it is pressed into firm engagement with rod 14 and the wall 22, thus effectively sealing `the interior of thecomponent 1. The O-ring 26 is held in place by t-he retainer plate 15 which is optionally press fitted into the end of bushing 10. In addition to acting as a seal, the O-ring 26 serves to provide `additional exibility in the suspension of the tuning piston 13. The flexibility of the O-ring allows the slight radial movements of the rod 14 which are required to avoid mechanical interferences between the piston 13 and cylinder 6 as the piston is traversed.

FIGURE 2 shows a modification of the adjusting mechanism shown in FIGURE l. In this modification the threaded discs 16 and 17 and the spring 18 shown in FIGURE 1 are replaced by the adjustment head 28. Adjustment head 28 has an external thread 31 and has a slot 29 for accommodating a screwdriver or other means for adjustment. The flexible rod 14 is centrally attached to the head 28. A slot 30 is cut diametrically across the adjustment head. The depth of the slot is proportioned so that the equilibrium of internal stresses which are normally present in a cold drawn metallic rod is rupset causing the split portions to spring outward from the center. The slot 30 is cut after the screw thread 31 is machined.

Hence, in order to thread the head 28 into the internal Y screw thread 20 it is necessary yto squeeze the sprung bifurcated portion back to its original dimensions. After assembly the split segments of head 28 exert radial tenwith the internal thread 20. Thus the bifurcated threaded adjustment head 28 coacts with the internal thread 20 to minimize backlash and to provide sufficient frictional resistance to turning toprevent movement of the connected elements adjustment head 28, rod 14, and piston 13 under conditions of shock and vibration.

Referring to FIGURE 3, this second embodiment 57 is si-milar in principle to the first embodiment, the chief difference 'being that in the second embodiment the piston V40 traverses the length of the cylinder without rotating while in the first embodiment the piston 13 rotates as it traverses the length of the cylinder, as will be readily apparent from a comparison of FIGURES 1 and 3.

FIGURES 1 and 3 both depict panel mounted type trimmer capacitors. In FIGURE 3 the dielectric cylinder 35 and its cap 32 correspond exactly with the cylinder 6 and cap 2 of the first embodiment. Likewise, the piston 40 corresponds to the piston 13 of the first embodiment. However, the flexible rod 41 differs from rod 14 of the first embodiment in that the former has a generally angular cross section rather than a circular cross section. Corresponding to the angular section of the rod 31, shown rectangular in FIGURE 3, the opening in the bushing 55 has a matching shape which prevents rotation of rod 41 duri-ng adjustment of the capacitor as is further described below.

The bushing 38 of FIGURE 3 further differs from mounting bushing 8 of FIGURE 1 in that the bore 46 is unthreaded. An adjusting sleeve 52, with a screwdriver slot 54 in its closed end and an internal screw thread 53 is rotatably fitted in the bore 46 of bushing 38. A disc type spring 51 is located between the open end of the adjusting sleeve 52 and the end face of bore 46. This spring acts to push the sleeve 52 against the spun over edge 56 of bushing 38, thus removing backlash between the sleeve '52 and bushing 38. The discs 43 and 44 and the spring 4-5 in FIGURE 3 correspond with their counterparts discs 24 and 25 and spring 18 in FIGURE 1 except that they Vare restrained from rotating by the rod 41 which in turn is restrained from rotating by the bushing 55. When the adjusting sleeve S2 is rotated the elements vdiscs 43 and 44, spring 45, rod 41 and piston 40 traverse longitudinally without rotation, due to the coaction between the external threads 48 and 49 on the discs 43 and 44, the internal thread 53 of the adjusting bushing 52, and to the rotational restraining action of the bushing S5 on the angular rod 41.

As in the first embodiment, the O-ring50 and the O-ring retaining plate 42 act to seal olf the interior of the component, and to contribute to theexibility of the suspension of the piston. The O-ring 50 conforms to the shape of the cross section of the rod 41, and it is compressed between the retaining plate 42 and-the bushing 55.

FIGURE 4 shows a `further modification of the adjustment mechanism. It differs from the mechanism shown in FIGURES 1 and 3 in that the leaf spring 18 or 45 is replaced by the coil spring 59. The coil spring 59 is compressed between, but not vattached to, the externally threaded discs 58 and 60. The flexible rod 41 has an angular cross section in the portion of its length that engages the discs `58 and 60. As shown in FIGURE 7, rod 41 passes through dise 58 which has a hole essentially conforming in shape to the Icross section of the rod but said` hole is slightly larger than rod 41 so that there is a slip fit `between the rod 41 and disc 58. The end of rod 41 is centrally attached to disc 60. Thus the coaction of the rod 41 and the discs 58 and 60 is such that disc 58 is free to move longitudinally with respect to disc 60 but it is constrained so that it vcannot rotate with respect to disc 60. The internally threaded element 61 corresponds to bushing 10 of FIGURE 1 when this adjustment mechanism is used with the first embodiment, and to adjustment sleeve 52 of FIGURE 3 when it is used with the second embodiment. As in the adjustment mechanism shown in FIGURES l and 3 the spring member 59 produces axial tension between the internal a-nd external threaded elements to minimize backlash and to produce friction torque -between the threaded elements.

While I have disclosed preferred embodiments of the invention, .and have indicated various changes, omissions and additions which may be made therein, it Will be apparent that various other changes, omissions and additions may be made in the invention without departing from the scope and spirit thereof.

I olaim:

An adjustable reactive component having:

(a) a hollow longitudinal dielectric cylinder bearing a reactive element,

(b) a reactance varying member arranged for slidable movement within said dielectric cylinder with close tolerances therebetween and arranged to telescope over,

(c) a cylindrical tube having a screw threaded bore, an integral flange on which is attached the dielectric cylinder, and an externally threaded stud,

(d) disposed in the threaded bore of said cylindrical tube, propulsion means comprised of two threaded discs resiliently 4biased into engagement with threads of the bore of the tube by a spring between the discs which exerts axial tension and prevents relative rotation between the discs, Y

(e) a flexible member -connecting the propulsion means to the reactance varying member.

References Cited by the Examiner UNITED STATES PATENTS 2,537,985 1/ 1951 Godbey. 2,601,445 6/ 1952 Marakami 317-249 X 3,228,257 1/1966 Goldryn 74424.8

LEWIS H. MYERS, Primary Examiner.

E. GOLDBERG, Assistant Examiner. 

